The present invention generally relates to power hand tools and more particularly to a right angle attachment for the same.
Small rotary hand tools have been marketed for many years for use in carrying out woodworking and metal working tasks by hobbyists as well as commercial artisans. Such small rotary hand tools generally have a motor unit with a rotary output shaft that is adapted to connect to a number of accessories, a common one of which is a very long sheathed cable to which a sanding implement or rotary cutting implement can be attached. This enables the user to use the implement without lifting the drive unit itself which is often sufficiently large that it will cause fatigue to the user and also may interfere with desirable and effective use of the implement in close quarters.
The drive unit of many recent models of such rotary hand tools is relatively small and lightweight which is capable of being easily used by a user. Such rotary hand tools may be smaller than many small flashlights, i.e., they may have a diameter less than about two inches and a length of only about six inches. The tool has a small but powerful electric motor that drives an output shaft at high speed, and a rotary implement can be typically attached to the tool""s output shaft which is axially aligned with the tool. When the implement is attached directly to the output shaft, it is convenient for use in many applications, but it is also desirable for some applications that the orientation of the grinding or cutting implement be changed to a right angle relationship relative to the output shaft. In the present application, a xe2x80x9crightxe2x80x9d angle is intended to have a broader meaning than precisely 90xc2x0, and refers to orientations having the general appearance of a 90xc2x0 angle.
For such usage, a right angle attachment may be convenient for users to get to hard to get at areas and provide greater maneuverability that enables the attached implement to be handled and controlled more easily. Right angle attachments may be highly desirable for doing such application work as grinding, polishing an engine cylinder, drilling in tight areas, repairing household parts, grinding and sanding metal and wood, in addition to model railroad and airplane building and repair work.
Such right angle attachments have been designed for attachment to some tools, but many of such attachments are cumbersome to connect to the power unit tool in that they require tools such as screwdrivers, wrenches and the like to do so. Moreover, such attachments often cannot be angularly adjusted relative to the rotary hand tool and also do not operate in a smooth and aesthetically pleasing manner, i.e., they exhibit displeasing vibration, may overheat and are noisy during operation.
Accordingly, it is a primary object of the present invention to provide an improved right angle attachment for use with small rotary hand tools which is easily attached to the tool without special tools.
Another object is to provide such an improved right angle attachment that offers smooth reliable operating characteristics, in that it does not overheat or exhibit excessive noise or vibration.
Still another object of the present invention is to provide such an improved right angle attachment that is adapted to use the original chuck of the rotary hand tool which can be removed from the tool itself and applied to the output shaft of the right angle attachment in a simple manner.
A more detailed object of the present invention lies in the provision for the improved right angle attachment being easily mounted to the hand tool by simply removing the chuck from the hand tool, screwing a mounting coupling assembly onto the rotary tool housing, screwing a driver nut onto the rotary tool output shaft, slipping the attachment onto the rotary shaft output shaft and rotating a mounting sleeve to tighten the same in place.
Another detailed object of the present invention is provide such an improved attachment which incorporates a superior coupling design for coupling the output shaft of the hand tool to the input shaft of the attachment which is axially aligned with the rotary hand tool output shaft. The coupling incorporates a flexible shaft that is inserted into a driver nut having a unique interior configuration which easily accepts the flexible shaft and which effectively couples the rotary tool output shaft and attachment input shaft in a non-slipping rotational drive relationship.
A corollary object lies in the provision of the flexible shaft being adapted to compensate for any minor misalignment of the rotary tool output shaft and the input shaft of the attachment which could otherwise cause vibration and noise were it not for the flexibility and design of the flexible shaft and its connection to the input shaft of the attachment.
Still another object of the present invention is to provide such an improved right angle attachment which can be angularly positioned relative to the rotary tool itself throughout a complete 360xc2x0 arc in increments that are relatively small. A corollary object is to provide such angular orientation capability that can be very simply achieved by merely loosening the mounting coupling, sliding the attachment off of the rotary tool, angularly reorienting it and sliding the attachment back onto the tool and retightening the mounting sleeve.
Another detailed object lies in the provision for using a driver nut (which is screwed onto the rotary tool output shaft) that has a relatively large number of internal grooves which cooperate with a square end portion of the flexible shaft that is inserted therein so that the right angle attachment can be easily attached to the rotary tool by sliding the attachment onto the rotary tool which simultaneously results in the flexible shaft being inserted into the driver nut without requiring any rotation of one or the other of the tool output shaft or the attachment output shaft.
Accordingly, the present invention provides an attachment for a power hand tool of the rotational type which has an output drive shaft and a tool case suspending the output drive shaft. The attachment includes a housing, a gear assembly having a flexible input shaft, an output shaft and a transmission between the flexible input shaft and the output shaft, the housing being configured for containing the flexible input shaft, and the transmission. A mounting coupling assembly includes an adaptor fixable to either one of the tool case or the housing, the adaptor having an opening through which the input shaft or the output drive shaft may pass for connection of the input shaft with the output drive shaft, and a mounting sleeve having a central opening for passing of the flexible input shaft or the output drive shaft and being configured for securing the adaptor to the corresponding other one of the housing or the tool case for attaching the attachment to the power hand tool.
In another embodiment, an attachment is provided for a rotary power hand tool which has an output drive shaft. The attachment includes a gear assembly having a flexible input shaft, an output shaft, a transmission between the input shaft and the output shaft, the flexible input shaft having a first end connectable to the output drive shaft, a hollow transmission input shaft at least partly containing the flexible input shaft and being in a fixed rotational coupling with the flexible input shaft adjacent to a second end of the input shaft, and a transmission gear being fixed to the hollow transmission shaft for transmission of rotational energy from the hollow shaft to the output shaft.